Activities of Oxygen in Liquid Fe-Co-Cr and Ni-Co-Cr Alloys

The equilibria of the reactions of oxygen dissolved in liquid Fe-Co-Cr and Ni-Co-Cr alloys with H2-H2O gas mixtures have been measured at 1600°C. Combining the experimental data with the previous results on the similar equiliblia in the systems of Fe-Co, Fe-Cr, Co-Cr, Ni-Co and Ni-Cr alloys, the relationships between the apparent equilibrium constant and the ternary alloying composition were determined, respectively. From these results, the isoactivity coefficient curves for oxygen were drawn in the ternary alloy field. The possibilities to predict the activity coefficient of oxygen in the ternary alloy from the interaction coefficients were examined.